Voltage compensator



Jan. 3, 1933.

J. G. SOLA VOLTAGE COMPENSATOR Filed Aug. 7. 1950 Patented vJan. 3, 1933l UNITED STATES yPATENT oI-Flclaz JOSEPH G. SOLA, F CHICAGO, ILLINOIS,ASSIGNOR TO `SOLA CORPORATION, OF CHICAGO, ILLINOIS, A CORPORATION OFILLINOIS VOLTAGE COMPENSATOR Application led August 7, 1930. Serial No.473,692.

My invention relates to voltage compensahereinafter pointed out. Thepreferred tors for alternating currents and it has for its means bywhich I have accomplished my Iobject the provision ofa new and improvedseveral objects are illustrated in the drawform and arrangement ofautomatically oping and are hereinafter specifically described.

erating parts adapted when connected t0 an lThat which I believe to benew and desire 55 alternating current line to deliver a current to coverby Letters Patent is set forth in the at reduced' voltage when thevoltage on the claims. line becomes too high and to deliver a current Inthe drawing at increased voltage when the voltageon the Fig. 1 is adiagrammatic view showing the line becomes too low; It is one of theobjects preferred form of my improved voltage com- 60 of my invention toprovide an improved conpensator, with certain parts broken away forstruction of simple form, comprising a coil clearness of illustration.mounted upon a core which provides a `re F lgs. 2 and 3 are face views0f the two coturn path, and comprising auxiliary core operating partsrespectively of the core of l5 means providing a shunt return path ofcommy improved construction as shown in Fig. 5

paratively much greater reluctance than that 1; and

' of said principal return path, with means Fig. 4 is a face view of amodified form of adapted as lsaid principal return path ap-y core means.A proaches saturation by reason of an increased Referring now to Figs.1, 2 and 3, in which voltage through said coil to have increasingcorresponding parts are indicated by the same 70 effect to oppose thecurrent through said coil reference characters, it will be seen that myand thus to cut down the voltage of the curapparatus comprisestransformer means in rent delivered. 'y the form o f an autoformer madeup of a pri- It is one of the objects of my invention, mary coil 10 anda secondary including the particularly in cases where it is desired tocoil 10 and an auxiliary coil portion 11, said 75 operate an electricaldevice at the normal coils being provided with core means as herevoltagedelivered by the alternating current 'after described. The primary coil10 is conline, to provide an improved arrangement for nected between theleads 12 and 13 of an alfirst stepping up the voltage, providing thusternating current line. A third coil 14 is confor the contingency thatthe line voltage may nected in series with the secondary coil of the sobe too low, and then cutting down such intransformer in such relation asto opposesuch creased voltage to the necessary extent, with secondarycoil, being wound in the opposite the arrangement such that when thevoltage direction about the core means. Leads 15 on the line is low theeffect of the voltage reand 16 are connected at opposite ends of theduct-ion means shall not be so great as that connected coils fordelivery of the load curof the voltage increasing means, and that rentfrom the device.

when the voltage on the line is high the effect The core of my improvedapparatus is all of the voltage reduction means shall be maof laminatedform, the several plates of which terially greater than that of thevoltage inare held together by means of clamping bars creasing means. l17 which in turn are connected to each oth- It is one of the objects ofmy invention er by means of bolts 18. One of the members to provide, anarrangement by which the of the complete core means is in the form ofgradual increase in the degreeof saturation a rectangular piece 19having inwardly exr of a principal return path as the voltage intendingarms 20 which are in spaced relation 4" creasesmay 'be utilized forcorrespondingly to each other so as to receive snugly between increasingthe effect of the means 'provided them a core bar comprising a wideportion 21 for cutting down the voltage of the current at one end anda-comparatively narrow poras delivered to the load apparatus'. l tion 22at the op osite end; In the construc- O It is another object of myinvention to imtion shown the p atesmaking up the core bar o provedevices of this type in sundry details 21--22 are connected together bymeans of a. 100

rivet 23. The bar comprising the portions 21 and 22 is rounded at oneen'd so as to have a snug fit within a groove 24 in the inner face ofone of the side bars of the rectangular core part 19. At its oppositeend, the `.core bar 21--22I is separated from the side of the rectangular part 19 by an air gap as shown at 25 ing the arms 2()k and therectangular core part 19, since the air gap at 25 causes the reluctanceof the auxiliary return path through the bar portion 22 to be so muchgreater than the reluctance through the principal return path comprisingthe arms 20 that there will be a very small proportion of the lines offorce passing through such auxiliary return path. As the voltagethroughthe primary coil 10 increases beyond the normal so as to causethe normal return path to approach closely to saturation, the proportionof lines of force passing through the auxiliary returnl path comprisingthe bar portion 22 and the air gap 25 increases rapidly.

With thel voltage through the primary coil 10 at normal, the voltagethrough the secondary coil comprising the coil parts -10 and 11 will befound to be Very materially higher, the voltage between the leads 15 and16, however, will be considerably lower on account of the inductancedrop through the coil 14 and the counter-voltage set up in said coil 14by the influence of the field in the auxiliary return path comprisingthe core bar portion 22. The strength of this counter-voltage isdirectly proportional to the strength of the field in the auxiliaryreturn path, which in turn is controlled by the reluctance of suchauxiliary returnpath as compared with the reluctance of the principalreturn'path. The size of the air gap 25, by which the reluctance of the.auxiliary return path isl controlled, is designed to be such that, whenthere is a normal voltage inthe coil 10, the increase in voltage in thesecondary coil 10.-11 brought about'by the use of the transformer willbe approximately equalled and offset so far as the voltage between theleads 15 and 16 is concerned by the decrease in the voltage between saidleads 'due to th'e inductance drop through the coil 14 and thecounter-voltage through said coil. Thus when there is a normalvoltagebetween the line leads 12 and 13 there will beapproximately thesame voltage between the load leads 15 and 16.

With the parts arranged for operation as v pass through such auxiliaryreturn path by reason of the close approach to saturation in theprincipal return path. This serves very materially to increase thecounter-voltage in the coil 14, with the result that a large proportionof the increase in the voltage through the coil 10 is offset and theincrease in volta e between .the leads 15 and 16 is caused to e verymaterially less than the increase through the coil 10.

When the voltage through the coil 10 falls to a point below the normal,the strength of the field in the auxiliary return path comprising thecore bar portion 22 is decreased,

and at the same time the degree `of saturation in the principal returnpath is lowered.

Under such conditions, the amount of the def crease in the strength ofthis field for a given drop in voltage is much smaller than the decreasefor a` similar drop in voltage when the degree of saturation in theprincipal return path is comparatively higher. When the voltage throughthecoil 1 drops below normal, the counter-voltage Ithrough the'coil 14serves to reduce the voltage between the leads 15 and 16, but notsufficiently to cause such counter-voltageA and the inductance dropthrough the coil 14 together to balance the increase in voltage in thetransformer. It follows, accordingly, that when there is such a drop involtage in the coil 10 below normal at the same time the voltage betweenthe leads 15 and 16 also drops below normal, but that the drop betweenthe leads 15 and 16 is very materially less than the drop through thecoil 10.

p It is thus seen that my improved apparatus serves to deliver betweenthe leads 15 and 16 a current of a higher voltage than .that of thecurrent flowing through the coil 10 when the voltage in such coil 10falls'below a predeter` mined normal and to deliver between said leads15 and 16 a current of a lower voltage than that of the current throughthe coil 10 when the voltage in such coil 10 rises above suchpredetermined normal.

In practicing my invention I havebuilt a device in accordance with theshowing of Fig. 1 for -use in connection ,with an alternating currentline having a normal voltage of 110 volts, such device being designed todeliver a normal load current ofthesame voltage. This device has beenfound to provide approximately a fifty per cent correction forvariations in line voltage. That is to say, when the voltage through thecoil 10 has fallen to 100 volts the voltage delivered through the leads15 and 16 has been found to be approximately 105 volts, and when thevoltage through the coil 10 has -risen to` 120 volts the voltage throughsaid leads 15 and 16 has been found toy be approximately 115 volts.

In this machine so built in accordance with the showing of Fig. 1 andoperating as above set forth, the primary coil 10 has 195 turns, thecoil portion 11 has 105 turns, giving the secondary coil complete 300turns, andthe coil 14 has 300 turns. The core bars 20 are of such widthas to cause a close approach to saturation therein when the line voltageis at the normal 110 volts. The air gap 25 is of such size as to causethe inductance drop through the coil 14 and the counter-voltage in saidcoil substantially to balance the increase in voltage produced by thetransformer, whereby the voltage between the leads 15 and 16 issubstantially 110 volts when the line voltage is 110 volts.

In the arrangement shown in Fig. 4, the core comprises a bar 26, witharms 27 extending at right angles thereto, and an arm 28 extending in-continuation of the bar 26. Upon the outer ends of the arms 27, thereare bars 29 parallel with the bar 26, the parts 26, 27, 28 and 29 beingformed integrally with each other. A separately formed bar 30 isprovided across the ends of the bars 29 and 26, and another separatelyformed bar 21 is provided at the opposite ends of the bars 29 in spacedrelation to the bar 28. In this arrangement, the principal return pathcomprises the parts 26, 27, 29 and 30, While the auxiliary return pathcomprises the parts 28, 31 and 29. The coils 10 and 11 are, of course,to be mounted on the bar 26, and the coil 14 on the arm 28, thearrangement being such that the operation and effect are the same asthose above described in connection with the construction shown in Fig.1.

The description of the construction and operation above applies to thepreferred form of my improved device, but the invention is not in anyWay limited to some of the features as there set forth. For example,While I prefer to proportion the arms 20 so that they shall have a closeapproach to saturation l when the voltage in the coil 10 approaches thenormal, it will be understood that my invention broadly is not limitedthereto, it being evident that a device arranged with a differentlyselected pointof saturation would have a field of usefulness. In thesame way, my invention broadly is not to be limited With respect to thesize of the air gap 25 whereby the counter-voltage and the inductancedrop are made to balance or oi'set the transformer increase in voltagewhen the line voltage is at normal strength. It might well be that thedesigner would prefer to have this balanced condition take place whenthe line voltage is either above or below such normal strength. Ingeneral, my invention is not to be limited to the form as shown anddescribed except so fa as the claims are so limited by the prior ar Iclaim-f- 1. In a voltage compensator, the combina- .tlon of a core,primary and secondary coils mounted on said core in transformer relationship and arranged so that the voltage normally impressed on thesecondary has a constant ratio to the voltage in the primary, a portionof said core means being of such reduced size as compared with theremaining -portions that upon the passage of the normal current ofnormal voltage through the primary coil said reduced portion of the coreshall have a close approach to saturation, auxiliary core meansproviding a shunt return path about said core portion of reduced sizefor carrying a portion of the flux thread-- ing said primary andsecondary coils, and auxiliary coil means mounted on said auxiliary coreand connected in series with said secondary coil in opposition theretoadapted by theaction thereon of the magnetic ux through said auxiliarycore to cut down the voltage through the connected secondary andauxiliary coils to a point well below the voltage normally impressed onsaidl secondary coil. a l

2. In a voltage compensator, the combination of a core providing aclosed magnetic circuit and comprising a portion of predetermined crosssectional size and the remaining port'on of greater cross sectionalsize, primary and secondary coil means mounted in transformerrelationship to each other on said core portion of greater crosssectional size adapted upon the passage of the predetermined normalcurrent of normal volt duce substantial saturation in said reducedportion of the core, auxiliary core means adjacent to said core portionof reduced size providing a shunt return path thereabout, and auxiliarycoil means mounted on said auxiliary core means and connected in serieswith said secondary coil in oppostion thereto.

3. In a voltage compensator, the combination of a core providing aclosed magnetic circuit and comprising a portion of predetermined crosssectional size and the rema'ning portion of greater cross sectionalsize, primary and secondary coil means mounted in transformerrelationship to each other on said core portion of greater crosssectional size adapted upon the passage of the predetermined normalcurrent of normal voltage through the pr'mary coil means to producesubstantial saturation in said reduced portion of the core, auxiliarycore means providing a shunt returnA path about said core portion ofreduced size, and auxiliary coil means lill) said core, auxiliarycoremeans providing anmounted on said auxiliary core meansinsubstantially non-inductive relationship to the magnetic flux passingthrough said core portion of reduced size and .connected in serles withsaid secondary coil means in opposition thereto. 4. In a voltagecompensator, lthe comb1na substantial saturation in said reduced portionof the core, auxiliary core means providing a shunt return path aboutsaid core port-ion of reduced size, and auxiliarymeans mounted onsaidauxiliary core means 1n sul) stantially axial alignment with saidprimar coil and connected in series with said secon ary coilinopposition thereto. l 5. In a voltage compensator, the combination ofa core comprising a straight bar and a return path portion cooperatingto provide a closedmagnetic circuit, primary and secondary coil meansmounted in transformer relationship on said straight bar adapted upon.the passage 'of the normal current of normal voltage through the primarycoil means to produce substantial saturation in at least a part of thereturn path portion of said core, auxiliary core means providing avshunt return path about said part of the first named return path inwhich substantial saturation is produced and arranged to have acomparatively much higher normal ,reluctance than that of the firstvnamed return path means, and auxiliary coil means'mountv ed on saidauxiliary core means and connected in series with said secondary coil inopposition thereto. i

6. In a voltage compensator, the combination of a core comprising astraight bar and a. return path portion connecting anintermediate partand one end of said straight bar in a closed magnetic circuit, primaryand secondary coil means mounted in transformer relationship on saidstraight bar adapted upon passage of the normal current of normalvoltage through the primary co'il means to produce substantialsaturation in lwith sald-secondarycoil means in opposition thereto.

. JOSEPH G. SOLA.

at least a part of the return path portion of l auxliary return pathfrom the opposite end of said straight bar to said lirst named returnpath portion and arranged in parallelV -shunt relation to said portionof the first namedreturn path' in which substantial saturation 1sproduced, and an auxiliary coil mounted on said opposite end portion ofsaid

